Biocidal foams

ABSTRACT

A biocidal foam product comprising a foam having incorporated therein a water insoluble thermoplastic copolymer consisting of an alpha olefin and an alpha, beta-ethylenically unsaturated carboxylic acid, said copolymer having at least one cationic biocidal agent ionically bonded to said copolymer.

RELATED APPLICATIONS

This application is related to copending application Ser. No. 433,488,filed Nov. 8, 1989 of Vaughn et al entitled "Biocidal Fluid Filters".

FIELD OF THE INVENTION

The invention relates to polymeric foams which are resistant tobiological attacks, are biocidal and/or have improved strength. Moreparticularly, the invention provides a means for preparing polyolefinresin, polystyrene, latex, urea, cellulosic, isocyanurate andpolyurethane foam structures, or the like, so as to be resistant tobiological attacks, are biocidal, and in some instances, are reinforced.

BACKGROUND OF THE INVENTION

The physical and mechanical properties of foams make them useful for awide variety of applications. Flexible foams have been used infabricating diapers, mop heads, sponges, and the like. More rigid andhigher density foams have been used for bedding, for example mattressesalso been used as replacement for wood. In each of the fields of use thefoams have been susceptible to biological attack and mechanical abuse.

It is well known that diapers, mop heads, mattresses, and the like, areutilized under conditions wherein the foams are subjected tomicroorganisms which cause odors, degrade the foam or result in anunsanitary condition. Rigid foams are commonly used outdoors or atlocations which promote growth of fungus and/or mold that degrade thefoams or render them unattractive.

There are many antimicrobial preparations for suppressing mold, mildewand odor-causing bacteria. Such preparations include solid biocideconcentrates as described in U.S. Pat. No. 4,086,297. The commercialpreparation of Morton Thiokol, Inc. sold under the trademark VINYZENE isan additive to plastics which comprises 10, 10¹ -oxybisphenozas that isactive against a broad spectrum of fungi and bacteria. The product is inthe form of a 2 weight percent solution in mineral spirits or methylethyl ketone and as a 5 weight percent blend in a thermoplastic resin.These products are used as biocides in the field of wood preservatives,swimming pools, food preservatives, sanitizers and disinfectants,industrial water treatment and plastics.

Biocides which are commercially available include active halogens, forexample chlorine, chlorinated isocyanurates, halophors and the like,phenolics, quaternary ammonium salts including alkylbenzyldimethylammonium chloride, where the alkyl group contains 12-18 carbonatoms and dimethyldialkylammonium chloride, where the alkyl groupcontains 8-10 carbon atoms.

These biocides however are leachable and can be lost in an aqueousenvironment.

There is a further need to provide some foams with reinforcement. It iscommon to provide high-density polyurethane foams with fiberreinforcement, such as fiberglass, wollastonite, etc. These reinforcingfibers are added together with fillers which include biocides,deodorizing agents and the like. The problem encountered in such casesis that the addition of fillers alters the physical characteristics ofthe foam.

U.S. Pat. No. 4,680,214 to Frisch et al, which is herein incorporated byreference, discloses a rigid polyurethane foam having suspended thereinfillers and reinforcing fibers. The fibers comprise fiber glass or yarnstrands which are near the surface.

U.S. Pat. No. 3,865,619 to Pennewiss et al discloses the preparation ofanti-fogging hydrophilic resin coatings of an ethylenically unsaturatedmonomer, an acrylic acid or methacrylic acid and a quaternary ammoniumsalt. The quaternary ammonium salt is not biocidal.

U.S. Pat. No. 3,437,718 and 3,970,626, which are herewith incorporatedby reference disclose suitable methods for preparing the precursorionomers which may be used in the present invention.

U.S. Pat. No. 4,661,634 to Vaughn et al which is herein incorporated byreference, discloses the use of particles and fibers for removingimpurities from quaternary ammonium salts.

The particles and fibers of Vaughn et al comprise an alpha olefincopolymerized with an olefinically unsaturated carboxylic acid whichforms a "quat acrylate copolymer" when combined with quaternary ammoniumsalts.

Application Ser. No. 157,202 filed Feb. 17, 1988 of Patton et alentitled, "Polymer Salt Complex for Fiber or Fabric Treatment", which isherein incorporated by reference, discloses fabrics coated withcopolymers of alpha olefins and beta-ethylenically unsaturatedcarboxylic acids that are modified with quaternary ammonium salts.

U.S. Pat. No. 4,837,079 to Quantrille et al discloses an antimicrobiallyactive non-wooly web of cellulosic fibers bonded with a polymeric binderand having polyhexamethylene liquanide hydrochloride substantive to thefibers and bind as the antimicrobial agent.

U.S. Pat. No. 3,872,128 to Byck discloses an antimicrobial compositionof carboxyl-containing alpha-olefin polymers which have been partiallyneutralized with quinoline or pyridine derivatives. However, hydrogelsare not disclosed. The patent uses a melt process, a diffusion processand a dispersion process for preparing the antimicrobial compositions.In the melt process the reactants are refluxed with the removal ofwater. In the diffusion and dispersion processes the copolymer isstirred with a sodium hydroxide solution, treated with the antimicrobialagent and then treated with an acid. The acid prevents the formation ofa hydrogel.

The article of Ackart et al entitled "Antimicrobial Polymers", J.Bromed. Mater. Res., Vol. 9, pp 55-68 (1975) disclosescarboxy-containing alpha olefin copolymers having antimicrobial activitywhich are prepared to processes similar to those utilized in theaforementioned U.S. Pat. No. 3,872,128. The study eliminated theantimicrobial ionomers from consideration in applications such assurface treatments for hospital rooms, protective beds, pillowcoverings, etc. The major area of use was in products intended toprotect the article itself from microbial attack.

It should be understood that there is a distinction between thehydrogels of the invention which retain water and have the cationicbiocide ionically bonded to the copolymer, and a copolymer which ismerely swollen and then treated with a cationic biocidal agent withoutforming a hydrogel. In the hydrogel formation with the biocidal agentthere are many carboxylic acid sites available for bonding.

The hydrogel is formed when the solution of cationic biocidal agentcontacts the copolymer which is swollen with the base and water remains.Contacting the swollen copolymer or hydrogel with an acidic solution orrefluxing off the water during ionic bonding prevents the hydrogel fromforming.

SUMMARY OF THE INVENTION

The present invention relates to polymeric foams which are resistant tobiological attacks, are biocidal and/or have been improved byincorporating therein fillers comprising particles or fibers of anionomer or copolymer of an alpha-olefin having the general formulaR--CH═CH₂ where R is selected from the group consisting of hydrogen andalkyl radicals having from 1 to 8 carbon atoms, and an alpha,beta-ethylenically unsaturated carboxylic acid which has been modifiedby at least one cationic biocidal agent ionically bonded therewith. Theacid monomer content of the copolymer is preferably from about 5 to 50mol percent based on the copolymer.

Advantageously, the biocidal copolymer is a hydrogel. Preferably, thebiocidal groups are uniformly distributed throughout the copolymer.Generally, when the copolymer is not a hydrogel the biocidal groups arefound only on the surface of the copolymer. Utilizing microporous orcellular copolymers or particles provides a greater surface area tocontact the microorganisms and to carry the biocidal agent. However,hydrogels carry a greater amount of the biocidal agents.

The cationic biocidal agents which are capable of being ionically bondedwith the copolymers of the invention to form the biocidal particles andfibers include (CH₃ O)--Si--CH₂ --R--N--R R' X, wherein R is loweralkyl, R' is an alkyl of 16 to 25 carbon atoms and X is a halide,monoalkyltrimethyl ammonium salts such as cetyltrimethyl ammoniumbromide (CTAB), alkyltrimethyl ammonium chloride (commercial availableas ARQUAD 16), monoalkyldimethyl benzyl ammonium salts which arecommercially available as BTC 824, HYAMINE 3500, and RISEPTIN(dodecyldimethyl-3,4-dischlorobenzyl ammonium chloride), dialkyldimethylammonium salts, heteroaromatic ammonium salts such as cetylpyridiumhalide, alkylisoquinolinium bromide, bis-quaternary salts such as1,10-bis (2-methyl-4-amino-quinolinium chloride)-decane, polymericquaternary ammonium salts such as poly[oxyethylene (dimethylimino)ethylene (dimethyliminio)-ethylenedichloride], 2(4-thiozolyl)benzimidazole, N[alpha(1-nitroethyl)benzyl] ethylenediamine,6-chloro-9[4-diethylamino-1-methylbutyl amino]-2-methoxy acridinedihydrochloride, and the like.

The preferred biocidal agents used in modifying the copolymer andionomer used in the invention are selected from the group consisting ofalkylbenzyldimethyldialkylammonium halide, wherein the alkyl groupcontains 8-10 carbon atoms, and dimethydialkylammonium halide, whereinthe alkyl group contains 12 to 18 carbon atoms. Advantageously, thebiocidal agent forms about 30-50% by weight of the reaction product.

The biocidal agent modified copolymers and ionomers of the invention canbe prepared by reacting an ionomer or copolymer with a suitable biocideby milling, melt blending, slurrying the polymer with a solution of thebiocidal agent of the invention or by passing an alkaline solution ofthe biocidal agent through a fabricated article of the ionomer orcopolymer. Preferably, the ionomer or copolymer is made into a hydrogelby being treated with the biocidal agent.

The copolymer or ionomer may be blended with other thermoplasticmaterials prior to reaction with the biocidal agent to provide a fiberor particle characteristic for use in a specific environment.

Suitable thermoplastic materials include polyolefins, for example,polyethylene, polypropylene, and the like, polyvinyl chloride, polyvinylacetate, polyvinylidene chloride, and the like.

Since the biocidal copolymers or ionomers of the invention are capableof killing on contact a broad spectrum of microorganisms, yeasts, fungiand molds, they provide foams in which they are incorporated withsanitizing and deodorizing characteristics. However, when the modifiedcopolymer is in fiber form, it is capable of providing reinforcement sothat other reinforcing agents need not be added.

The modified copolymer may be utilized in an amount of about 5 to 50% byweight of the total composition depending upon the particular foam andwhether or not the copolymer comprises particles or fibers.

It is understood that the term particle is meant to include fineparticles, powders, platelets and the like. The fibers may be short orlong strands. A combination of the various forms may also be utilized.

Also, the term "copolymer" as used herein is meant to include ionomers,partially neutralized ionomers and copolymers having substantially allcarboxylic acid groups available for ionically bonding with a biocidalagent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention a foam is provided havingincorporated therein particles and/or fibers of a copolymer comprised ofan alpha olefin and an alpha, beta-ethylenically unsaturated carboxylicacid or an ionomer of said copolymer which is reacted with a cationicbiocidal agent capable of forming an ionic bond therewith. In accordancewith a preferred embodiment of the invention, the biocidal agent is aquaternary ammonium salt selected from the group consisting ofalkylbenzyldimethylammonium halide, wherein the alkyl group contains 12to 18 carbon atoms and dimethyldialkylammonium halide, wherein the alkylgroup contains 8 to 10 carbon atoms. Preferable of the quaternaryammonium salts is dimethyldidecyl ammonium chloride.

Examples of suitable olefins include ethylene, propylene, butene-1,pentane-1, hexane-1, heptane-1, 3-methylbutene, pentane-1, and the like.

Examples of suitable acid monomers include acrylic acid, methacrylicacid, ethacrylic acid, itaconic acid, maleic acid, fumaric acid, andmaleic anhydide. Maleic anlydide is not a carboxylic acid but it can beconsidered an acid for the purpose of the invention because itsreactivity is that of an acid. Similarly, other monoethylenicallyunsaturated anhydrides of carboxylic acid can be used.

The copolymer base need not necessarily comprise a two componentpolymer. Thus, although the olefin content of the copolymer should be atleast 50 mol percent, more than one olefin can be employed to providethe hydrocarbon nature of the copolymer base. Additionally, othercopolymerizable monoethylenically unsaturated monomers, illustrativemembers of which are mentioned below in this paragraph, can be employedin combination with the olefin and the carboxylic acid comonomer. Thescope of base copolymers suitable for use in the present invention isillustrated by the following examples: ethylene/acrylic acid/carbonmonoxide copolymers, ethylene/acrylic acid copolymers,ethylene/methacrylic acid copolymers, ethylene/itaconic acid copolymers,ethylene/methyl hydrogen maleate copolymers, ethylene/maleic acidcopolymers, ethylene/acrylic acid/methyl methacrylate copolymers,ethylene/methacrylic acid/ethylacrylate copolymers, ethylene/itaconicacid/methyl methacrylate copolymers, ethylene/methyl hydrogenmaleate/ethyl acrylate copolymers, ethylene/methacrylic acid/ vinylacetate copolymers, ethylene/acrylic acid/vinyl alcohol copolymers,ethylene/propylene/acrylic acid copolymers, ethylene/methacrylicacid/acrylonitrile copolymers, ethylene/fumaric acid/vinyl methyl ethercopolymers, ethylene/vinyl chloride/acrylic acid copolymers,ethylene/vinylidene chloride/acrylic acid copolymers,ethylene/vinylidene chloride/acrylic acid copolymers, ethylene/vinylfluoride/methacrylic acid copolymers, andethylene/chlorotrifluoroethylene/methacrylic acid copolymers.

The copolymers may also, after polymerization but prior to ioniccrosslinking, be further modified by various reactions to result inpolymer modifications which do not interfere with the ioniccrosslinking. Halogenation of an olefin acid copolymer is an example ofsuch polymer modification.

The preferred base copolymers, however, are those obtained by the directcopolymerization of ethylene with a carboxylic acid comonomer. Suchcopolymers, when converted to hydrogels, provide unexpected advantages.

The ionic copolymers are obtained by the reaction of the acid copolymerwith a suitable base or an ionizable basic metal compound which is wellknown and referred to as neutralization. The ionomers are those in whichat least 5 percent by weight, preferably from about 20 to about 100percent by weight of the acid groups have been neutralized. Metal ionswhich are suitable for neutralizing the copolymers of the presentinvention are selected to make porous particles from monovalent,divalent and trivalent metals of Groups I, II, IV-A, and VIII of thePeriodic Table of Elements. Specific examples of suitable monovalentmetal ions are selected from Na⁺, K⁺, Li⁺, Cs⁺, Rb⁺, Hg⁺, and Cu⁺.Examples of suitable divalent ions include Be⁺², Mg⁺², Ca⁺², Sr⁺², Ba⁺²,Cu⁺², Cd⁺², Hg⁺², Sn⁺², Pb⁺², Fe⁺², Co⁺², Ni⁺ 2, and Zn⁺². Trivalentmetal ions suitable for use herein are selected from the group of Al⁺³,Sc⁺³, Fe⁺³, and Y⁺³. However, in making hydrogels of the ionomerparticles by reaction with a quaternary amine, ionomers of monovalent ordivalent should be used.

The preferred metals suitable for neutralizing the copolymers usedherein are the alkali metals of Group I, particularly cations such assodium, lithium, potassium, and alkaline earth metals of Group II, inparticular, cations such as calcium, magnesium, and zinc. It should benoted that more than one metal ion may be incorporated into thecopolymer in certain applications. Suitable bases for neutralizing thecarboxylic acid groups include, inter alia, ammonia, amines, alkalimetal hydroxides, alkaline earth metal hydroxides, other metalhydroxides, metal oxides and the like.

A convenient method of preparing ionomers is disclosed in U.S. Pat. No.3,437,718, issued to Rees, entitled, "Polymer Blends". In particular,the metal compound is added to an alphaolefin/alpha, beta-ethylenicallyunsaturated carboxylic acid and the mixture is milled at a temperatureof from about 140 to about 180° C. for about 15 minutes or until thereaction proceeds to completion. The disclosure of U.S. Pat. No.3,437,718 is incorporated herein by reference.

Another method of preparing the alkali metal salts of copolymers hereinis disclosed in U.S. Pat. No. 3,970,626, issued to Hurst et al, on July20, 1976; the disclosure of which is incorporated herein by reference.In particular, the reference teaches a hydrolysis process for preparingaqueous copolymer salt emulsions of alpha-olefin, alpha,beta-ethylenically unsaturated carboxylic acids by suspending aparticular alpha-olefin, alpha beta-ethylenically unsaturated carboxylicacid ester interpolymer in water having an alkali metal dissolvedtherein and heating said mixture to a temperature of at least 180° C.under autogenous pressure for a period of time sufficient to enable thealkali metal to react with a sufficient portion of the ester groups ofthe copolymer to render said copolymer emulsifiable in the aqueousalkali medium.

According to the present invention the copolymer or ionomer is firstformed into the pertinent structure, that is, fibers, particles, etc.The copolymer or ionomer is treated with a base and then ionicallybonded with a biocidal agent. The reaction which takes place is areplacement reaction wherein the metal group of the ionic polymer isdisplaced by the biocidal agent. Preferably, the acid copolymer isreacted with a base to form an ionomer and the quaternary ammoniumcompound and/or other biocidal agent is then ionically bonded to thecopolymer thus producing a hydrogel. With a hydrogel there is a greaterdistribution of the biocidal agent throughout the copolymer.

More specifically, a fabricated article is swollen/digested with a hot(50-70° C.) aqueous base (such as 2.0 wt. % sodium hydroxide) to form aporous ionomer. The excess caustic is rinsed away with deionized waterand then the swollen/digested polymer is treated with an aqueoussolution containing the cationic biocidal agent (for example, aquaternary salt). The biocidal agent is becomes ionically bonded(interchanged for sodium which is released into the solution), thusproducing a hydrogel.

The biocidal polymer is preferably washed with deionized water to removeany labile or unreacted salts. The necessity of this step depends on theintended uses of the product.

Alternatively, ethylene-acrylic acid copolymers (or an equivalent) isextruded (85-88° C.) into a strand alone or blended with anotherthermoplastic with some orientation (including "cold-drawing" the strandat a temperature below that at which stress relaxation can occur) priorto chopping the strand into strand chopped pellets. The pellets areswollen for 2-5 hours in 2.0 wt. % sodium hydroxide aqueous solution ata temperature of 50-65° C. to induce conversion to the ethylene-sodiumacrylate ionomer (ion exchange thermoplastic pellet). The caustic isdrained, the pellets are washed with deionized water and hammered intofiber using a hammermill. The resulting fiber are water washed and sizedby pumping an aqueous slurry of the hammered fiber through screens ofdifferent mesh. Generally it is desirable to separate the fibers of 50mesh and smaller from those of a coarser size.

Alternatively, ethylene-acrylic acid copolymers (or an equivalent) isextruded (185-190° F.) into a strand with some orientation (includingcold drawing the strand at a temperature below that at which stressrelaxation can occur) prior to chopping the strand into strand choppedpellets. The pellets are swollen for 2-5 hours in 2.0 wt. % sodiumhydroxide aqueous solution at a temperature of 50-65° C. to induceconversion to the ethylene-sodium acrylate ionomer (ion exchangethermoplastic pellet). The caustic is drained, the pellets are washedwith deionized water, treated with an aqueous solution of the cationicbiocidal agent and then hammered into fiber, i.e. fibrillated, using ahammermill. The resulting fibers are water washed and sized by pumpingan aqueous slurry of the hammered fibers through screens of differentmesh. Generally it is desirable to separate the fibers of 50 mesh andsmaller from those of a coarser size. The coarse fiber (18-50 mesh) aresuitable for use in rigid foam structures while the fine fiber (>50mesh) is suitable for example in mattresses.

PREPARATION OF FOAM

The foams which may be utilized in the invention may be formulated so asto be flexible, semi-rigid or rigid in nature. The foams of theinvention can take the form of pellets, coatings, pads, seat pads,cases, structural material, and the like.

The polyurethane foams employed in the present invention are preferablyprepared from a polyol reactant, which is mixed with an aqueouspolyisocyanurate reactant. The foams thus generated are characterized bya crosslinked molecular network.

The polyol is reacted with a polyisocyanate in a convention mannertogether with the biocidal fibers and/or particles of the invention. Thereaction can be carried out in an inert atmosphere, such as under anitrogen blanket, at atmospheric pressure and at a temperature in therange of about 0° Celsius to about 120° Celsius for a period of timeranging up to about 20 hours, depending upon the temperature and thedegree to which the reaction mixture is agitated. The reaction can alsobe carried out under ambient conditions.

The reaction is effected using stoichiometric amounts of reactants. Itis desirable, however, in some cases to use an excess of polyisocyanatein order to insure complete reaction of the polyol. The ratio ofisocyanate groups to hydroxyl groups is generally between about 1 toabout 4 isocyanate groups per hydroxyl group.

The polyisocyanates employed in the reaction may include a polyarylpolymethylene polyisocyanate as defined in U.S. Pat. No. 2,683,730, forexample, benzene 1,3,5-triisocyanate; chlorophenyl diisocyanate;3,3'-dimethoxy-4,4'biphenylenediisocyanate, and the like.

Readily available aromatic diisocyanate, aliphatic and cycloaliphaticdiisocyanates and polyisocyanates or mixtures thereof, having a highdegree of activity, are suitable for use in the reaction.

Polystyrene foams used in the invention may be prepared by conventionalmethods while incorporating therein the biocidal fibers and/or particlesof the invention.

Presently known techniques of preparing expanded polystyrene include theextrusion of a thermoplastic resinous gel in admixture with a volatileraising or blowing agent into a region of lower pressure where thevolatile raising agent vaporizes and forms a plurality of gas cellswithin the extruded gel. The extruded foamed gel is subsequently cooledto form a self-supporting cellular foamed body. A wide variety offoaming or raising agents are known. These foaming or raising agentsprimarily fall into the class of aliphatic hydrocarbons such as butane,hexane, heptane, pentanes and the like, as well as gases which aresoluble in a polymer under pressure such as carbon dioxide.

Beneficially, certain fluorinated hydrocarbons are used such astrichlorofluoromethane, trifluoromethane and the like, as well aschlorohydrocarbons such as methylene chloride. Many of these raisingagents are found to be satisfactory with various polymeric materials.

The following examples are illustrative of the invention, but are not tobe construed as to limiting the scope thereof in any manner. Thepercentages disclosed relate to percentage by weight.

EXAMPLE 1 A. Preparation of Biocidal Fiber from Melt SpunEthylene/Acrylic Acid Copolymer

An ethylene/acrylic acid copolymer (melt index of 300 and acrylic acidcontent of 20 wt. %) was melt spun at 147° C. on fiber spinningequipment used for polyethylene spinning (spinnerette with 34 holes of600 microns diameter). The copolymer was spun into a continuous filamentand hauled off onto spools during spinning. A filament of 26-28 microndiameter was spun.

A six gram sample of the filament was chopped to 6 mm. lengthmechanically. The chopped fiber was placed in a stirred beakercontaining an excess of 0.5 N NaOH solution. The mixture was digestedfor 5 hours at 55° C. to convert the fiber to a microporous, wettablefiber of ethylene-sodium acrylate. The solution was cooled. The causticwas drained and the fiber was washed with water to remove excesscaustic.

The swollen fiber was diluted in water to form a slurry and poured intoa 100 ml. burette and the excess water drained. A 500 ml. solution of5.0 wt. % of dimethyldidecylammonium chloride was slowly recirculatedthrough the fibrous bed continuously at a flow rate of thirty bedvolumes per hour flow rate using a masterflex variable speed peristalticpump. After a six hour exposure time, distilled water was purged throughthe column to clean the fibers thoroughly (1.5 liters of purge water).The fibers were removed from the burette and air dried. A nitrogenanalysis showed the new product to have 1.03 wt. % nitrogen(corresponding to 26.5 wt. % of dimethyldidecylammonium acrylate, abouta 34% conversion to the biocidal quat form). Sodium analysis of thefiber (before and after treatment) showed that the residual sodium wasreduced from 4.2 wt. % to 21 ppm. (99.95% replacement of availablesodium with the dimethyldidecylammonium cation).

B. Samples of the above melt spun ethylene-acrylic aciddimethyldidecylammonium acrylate were submitted to a Biolab for testing.Four types of microorganisms were tested (petri dish tests containingagar and a few fibers were inoculated with microorganisms to determineif the organisms would form colonies or die). Complete kill was observedfor the four organisms tested (Mucor miehei, Candida albicans, Pirciculariacryzac, Aspergillis niger). The fiber definitely exhibited biocidalproperties and the dimethyldidecylammonium acrylate groups were linkedto the biocidal properties. The fibers could be placed in a sponge orsponge mop. The biocidal fibers were also effective against Pseudomonasaeruginosa, brewers yeast, E. coli and S. aureus.

EXAMPLE 2 A. Preparation of Biocidal Fiber from Melt Blown EthyleneAcrylic Acid

An ethylene/acrylic acid copolymer (melt index of 300 and acrylic acid(A.A.) content of 20 wt. %) was melt blown at 147 degrees Celsius andblown in high speed air into a mass. The diameter was 30 microns forthis melt blown filament.

A six gram sample of the melt blown filament was chopped to 5 mm lengthsmechanically and the melt blown fibers digested in 0.5 N. causticsolution at 55° C. for 5 hours. The procedures of Example No. 1 wereused to produce a white, fiber containing 1.06 wt. % nitrogen. Thiscorresponded to a about 34% conversion to the biocidal quat form, andrepresented a complete interchange of the available sodium groups fordimethyldidecylammonium cation groups. The fiber obtained corresponds toa composition containing 27.3 wt. % dimethyldidecylammonium acrylate.

EXAMPLE 3

A. Preparation of Biocidal Particles from Hammermill Ground Fiber:

An ethylene-acrylic acid copolymer (300 melt index/20 wt. % AA) wasextruded at 92° C. into strand, and then ground chopped into particles.

The particles were placed in a digestion bath containing 2 wt. % causticheated to 55° C. and allowed to digest for 5 hours. The particles wereremoved and thoroughly washed with water.

A 12.0 gram portion of the particles was placed in a 100 ml. burette andrinsed thoroughly with water by pumping 2 liters of purge water slowlythrough the particle bed. A white, fibrous bed of about 11 inches beddepth was obtained.

A 500 ml. portion of solution containing 5.0 wt. % ofdimethyldidecylammonium chloride was recirculated through the bed forsix hours at a flow rate of 30 bed volumes per hour.

After the six hour reaction period, the bed was drained and thoroughlywashed with 3 liters of deionized water and then further rinsed byrecycling four hours with water to remove any trace chemicals. Theproduct was removed from the column and air dried. Nitrogen analysis ofthe sample showed 0.49 wt. % nitrogen (corresponding to about 15%conversion to the biocidal quat form).

B. The particles were tested for biocidal activity and it was observedthat addition of small amounts of the particles to agar gave completekill to the four test organisms of Examples 1.

EXAMPLE 4

A flexible reinforced polyurethane foam was prepared by mixing in aquart (0.95 1) size paper cup 100 parts by weight (pbw) of a polyethertriol having an average molecular weight of about 3000 commerciallyavailable from The Dow Chemical Company as Voranol 3137. 4.3 pbw water,1.2 parts of L-540, a silicone surfactant commercially available fromUnion Carbide Corp., and Dabco 33 LV a mixture of 33% by weight oftriethylenediamine in dipropylene glycol commercially available from AirProducts Co. Then a separate mixture of 1.715 parts of stannous octoatecatalyst and 45.2 ml of an 80/20 mixture of 2,4-/2,6-toluenediisocyanateare stirred with the polyol-containing mixture in a one-half gallon(1.89 1) cardboard cup. Stirring was stopped when the reaction started.The resultant mixture foamed and filled a cup containing 1 part byweight of the fibers of Example 1 to give a flexible foam withreinforcing and biocidal fibers covering the outside surface.

EXAMPLE 5

The procedure of Example 4 was followed except that 5 parts of thebiocidal fibers of Example 1 and 5 parts of the biocidal particles ofExample 3 were utilized. Also, the reaction mixture was continuouslymixed when the reaction started.

The addition of biocidal particles or platelets improves biocidalkilling characteristics without any substantial loss in foam properties.

In the following examples, a plurality of foams are prepared undervarying conditions. In each case, the polymer is heat plastified in anextruder substantially in the manner of U.S. Pat. No. 2,669,751 and avolatile fluid blowing agent injected into the heat plastified polymerstream. From the extruder the heat plastified gel is passed into amixer, the mixer being a rotary mixer wherein a studded rotor isenclosed within a housing which has a studded internal surface whichintermeshes with the studs on the rotor. The heat plastified gel fromthe extruder is fed into the end of the mixer and discharged from theremaining end, the flow being in a generally axial direction. From themixer, the gel passes through coolers such as are described in U.S. Pat.No. 2,669,751 and from the coolers to a die which extrudes a generallyrectangular board. After extrusion, a foam of an acceptable, density,cell size, compressive strength, water vapor permeability and thermalconductivity is obtained.

EXAMPLE 6

Polystyrene having a viscosity of 14 centipoises (measured as a 10percent solution in toluene) is fed to an extruder at the rate of 541parts by weight per hour together with a mixture of the fibers fromExample 1 and the particles from Example 3 so as to amount to 20% of theresulting foam. The blowing agent consists of a 1:1 by weight mixture ofmethyl chloride and dichlorodifluoromethane which is injected into theheat plastified polymer prior to its entry to the mixer. A total feed of20.3×10⁻⁴ moles of blowing agent per gram of polystyrene is added as anucleator. A stable fiber reinforced rectangular board is extruded at atemperature of 121.5 degrees Celsius having a cross-sectional dimensionsof 2.25×24 inches. The fibers and particles were distributed fairlyuniformly throughout the foam.

EXAMPLE 7

A polyol blend was prepared by blending 60 parts of a rigid polyolVaronol 360 (polyether triol, equivalent weight 155, hydroxyl number359, and hydroxyl functionality of 4-6, Dow Chemical Co.), 10 parts of aflexible polyol, Pluracol 220 (polyether triol equivalent weight 2093,hydroxyl number 27, BASF Wyandotte Corp.) and 30 parts of an aromaticpolyether polyol, Terate 202 (equivalent weight 126, hydroxyl number315, and a hydroxyl functionality of two, Hercules, Inc.).

Into the polyol blend, 1 part of silicone surfactant, DC-193 (DowCorning Corp.), 0.06 part of urethane catalyst Dabco R-8020 (AirProducts), and 0.06 part of urethane catalyst T-12 (dibutyltindilaurate), and methylene chloride as a blowing agent to give a densityof about 39.7 lbs/cu. ft., were blended and then approximately one-halfof the filler (54.9 parts trishydrated alumina (Hydrafil) and 27 partsof the particles of Example 3 was added into the blended substance tomake Component-I.

Component-II was prepared by blending polymeric isocyanate PAPI 27,equivalent weight 133.3 (Dow) and the remainder of the filler. Theisocyanate Index was 110.

The components I and II were weighed separately, mixed, and about 5percent by weight of one-half inch long chopped fibers of Example 1 wereadded and stirred for about 25 seconds, and then charged into a mold andheated at 70° Celsius for 5 minutes.

The composite has its two opposed main surface layers reinforced byfiber strands arranged longitudinally. The content of continuous fiberstand in the composite was ten percent, based on the total weight. Thisproduct was made up of fiber stands (small bundles of monofilaments)bundled together to form a large bundle of about three-sixteenths of aninch in diameter and these stands were kept at one-fourth inch intervalscenter to center, just beneath both surfaces.

The foam as it came out of the mold had a thickness of 1.25 inches and awidth of three inches and was cut into then inch lengths. The resultingproduct was suitable for use as a material of construction in lieu ofwood but with improved resistance to mildew.

What is claimed is:
 1. A foam structure having biocidal characteristics comprising a polymeric foam having incorporated therein a biocidal effective amount of biocidal particles and/or fibers comprising a water insoluble thermoplastic copolymer comprising an alpha olefin and an alpha, beta-ethylenically unsaturated carboxylic acid, said copolymer having at least one cationic biocidal agent ionically bonded thereto.
 2. The foam structure of claim 1 wherein said copolymer is a hydrogel.
 3. The foam structure of claim 1 wherein said copolymer is microporous.
 4. The foam structure of claim 1 wherein said biocidal agent is a quaternary ammonium salt selected from the group consisting of alkylbenzyldimethylammonium halide, wherein said alkyl group contains 12 to 18 carbon atoms, and dimethyldialkylammonium halide, wherein said alkyl group contains 8-10 carbon atoms.
 5. The foam structure of claim 4 wherein said quaternary ammonium salt is dimethyldidecylammonium chloride.
 6. The foam structure of claim 1 wherein said carboxylic acid component comprises 5 to 50 mol percent of said copolymer.
 7. The foam structure of claim 1 wherein said copolymer comprises an alpha-olefin of the general formula R--CH═CH₂, wherein R is selected from the group consisting of hydrogen and an alkyl group having from 1 to 8 carbon atoms.
 8. The foam structure of claim 1 wherein the alpha, beta-ethylenically unsaturated acid is selected from the group consisting of acrylic acid, methacrylic acid, ethacrylic acid, maleic acid and fumaric acid.
 9. The foam structure of claim 1 wherein said copolymer is the reaction product of ethylene and maleic anhydide.
 10. The foam structure of claim 1 wherein said alpha-olefin is ethylene.
 11. The foam structure of claim 1 wherein said copolymer is derived from an ionomer.
 12. The foam structure of claim 1 which is a mop head.
 13. The foam structure of claim 1 which is a mattress.
 14. The foam structure of claim 1 which is cushion.
 15. The foam structure of claim 1 which is a sponge. 